Title: Simulink Based Vehicle Cooling System Simulation;
1Simulink Based Vehicle Cooling System Simulation
Series Hybrid Vehicle Cooling System
Simulation 13th ARC Annual Conference May 16,
2007 SungJin Park, Dohoy Jung, and Dennis N.
Assanis University of Michigan
2Outline
- Introduction
- Motivation
- Objectives
- Simulation and Integration
- Hybrid vehicle system modeling VESIM
- Cooling system modeling
- Configuration of HEV cooling system
- Summary
3Vehicle thermal management and cooling system
design
- Motivation
- Additional heat sources (generator, motor, power
bus, battery) - Various requirements for different components
- Objective
- Develop the HEV Cooling System Simulation for the
studies on the design and configuration of
cooling system - Optimize the design and the configuration of the
HEV cooling system
Conventional Cooling System
HEV Cooling System
4Overview of Cooling System Simulation
- Cooling system model use simulation data from the
hybrid system model - Minimizes computational cost for optimization of
design and configuration
Driving schedule
HEV Cooling System Model
Hybrid Propulsion System Model VESIM
5Hybrid propulsion system configuration and VESIM
Engine 400 HP (298 kW)
Motor 2 x 200 HP (149 kW)
Generator 400 HP (298 kW)
Battery (lead-acid) 18Ah / 25 modules
Vehicle 20,000 kg (44,090 lbs)
Maximum speed 45 mph (72 kmph)
6Hybrid vehicle power management
Charging mode
Braking mode
Discharging mode
- Battery is the primary power source
- When power demand exceeds battery capacity, the
engine is activated to supplement power demand
- Engine / generator is the primary power source
- When battery SOC is lower than limit, engine
supplies additional power to charge the battery - Once the power demand is determined, engine is
operated at most efficient point
- Regenerative braking is activated to absorb
braking power - When the braking power is larger than motor or
battery limits, friction braking is used
7Vehicle simulation
Vehicle driving cycle
Vehicle simulation model VESIM
Cycle simulation results ( engine / generator /
motor / battery)
Motor Speed
Battery SOC
Engine Speed
Generator Speed
Generator Torque
Engine BMEP
Motor Torque
8Cooling system modelingConfigurations
Configuration A
HEV Cooling System Model in Matlab Simulink
9Guide Lines of Cooling system configuration
Criteria for system configuration
- Radiators for different heat source components
are allocated in two towers based on operation
group - The radiators are arranged in the order of
maximum operating temperature - Electric pumps are used for electric heat sources
- The A/C condenser is placed in the cooling tower
where the heat load is relatively small - Battery is assumed to be cooled by the
compartment A/C system due to its low operating
temperature (Lead-acid 45oC)
Component Heat generation (kW) Control Target T (oC) Operation group
Engine 190 120 A
Motor / controller 27 95 B
Generator / controller 65 95 A
Charge air cooler 13 - A
Oil cooler 40 125 A
Power bus (DC/DC converter) 5.9 70 C
Battery 12 45 D
Grade Load condition The heat sources that generate heat simultaneously during driving cycle are grouped together. Maximum speed condition / Lead-acid Grade Load condition The heat sources that generate heat simultaneously during driving cycle are grouped together. Maximum speed condition / Lead-acid Grade Load condition The heat sources that generate heat simultaneously during driving cycle are grouped together. Maximum speed condition / Lead-acid Grade Load condition The heat sources that generate heat simultaneously during driving cycle are grouped together. Maximum speed condition / Lead-acid
10Configurations
Configuration C
Configuration B
Power Generation
Vehicle Propulsion
11Modeling Approach
Component Approach Implementation
Heat Exchanger Thermal resistance concept 2-D FDM Fortran (S-Function)
Pump Performance data-based model Matlab/Simulink
Cooling fan Performance data-based model Fortran (S-Function)
Thermostat Modeled by a pair of valves Fortran (S-Function)
Engine Map-based performance model Matlab/Simulink
Engine block Lumped thermal mass model Matlab/Simulink
Generator Lumped thermal mass model Matlab/Simulink
Power bus Lumped thermal mass model Matlab/Simulink
Motor Lumped thermal mass model Matlab/Simulink
Oil cooler Heat exchanger model (NTU method) Matlab/Simulink
Turbocharger Map-based performance model Matlab/Simulink
Condenser Heat addition model Matlab/Simulink
Charge air cooler Thermal resistance concept 2-D FDM Fortran (S-Function)
12Modeling Approach Heat source
- Heat Input and Exchange Model for Engine Block
and Electric Components - Lumped thermal mass model
- Heat transfer to cooling path (Qint) and to outer
surface (Qext radiation and natural convection) - Engine
- Map based engine performance model
- Heat rejection rate as a function of speed and
load is provided by map - Turbo Charger
- Map base turbo charger performance model
- The temperature and flow rate of the charge air
as functions of speed and load are provided by
map
Schematic of Heat Exchange Model at Engine and
Electric components
Engine heat rejection rate
13Modeling ApproachHeat sources (cont.)
- Oil Cooling Circuit
- Heat addition model heat is directly added to
the oil - Heat rejection rate as a function of speed and
load is provided by map - Condenser
- Heat addition model heat is directly added to
the cooling air - Constant value is used for heat rejection rate
- Charge air coolers
- 2-D FDM-based model
- In contrast to radiator, heat transfer occurs
from air to coolant - Generator
- Heat generation is calculated using a 2D look-up
table indexed by speed and input torque - Lumped thermal mass model
14Modeling ApproachHeat sources (cont.)
- Motors
- Heat generation is calculated using a 2D look-up
table indexed by speed and input torque - Lumped thermal mass model
- Power bus
- Power bus regulates the power from electric power
sources and supply the power to electric power
sink - Heat generation is determined by battery and
motor power - Lumped thermal mass model
15Modeling ApproachHeat sinks
- Heat exchanger (radiator)
- Design variables
- Core size
- Water tube depth, height, thickness
- Fin depth, length, pitch, thickness
- Louver length, height, angle, pitch
- Based on thermal resistance concept
- 2-D Finite Difference Method
Structure of a typical CHE
Design parameters of CHE core
Empirical correlation for ha (by Chang and Wang)
Staggered grid system for FDM
16Modeling ApproachHeat sinks(cont.)
- Oil cooler
- Finned concentric pipe heat exchanger model for
Oil Cooler - Counter flow setup
- NTU approach is used to calculate the exit
temperature of two fluids
Schematic of Heat Exchange at Engine and Electric
components
NTU Method
17Modeling ApproachDelivery media (Coolant)
- Coolant Pumps
- The coolant flow rate is calculated with
calculated total pressure drop by cooling system
components and the pump operating speed - Performance map is used to calculate the coolant
flow rate - The mechanical pump is driven by engine and
electric pump is driven by electric motor
Efficiency
Flow rate
Efficiency
Flow rate
Performance Maps of Mechanical Pump
Performance Maps of Electric Pump
18Modeling ApproachDelivery media (Coolant)
- Thermostats
- Two way valve with Hysteresis characteristics
- Coolant flow rate to re-circulate circuit and
radiator are determined by the pressure drops in
each circuit
T/S valve lift with hysteresis
Valve lift curve of T/S
Coolant flow calculation based on pressure drop
19Modeling ApproachDelivery media (Oil/Air)
- Oil Pump
- Map based gear pump model for Oil Pump
- Cooling fans
- Total pressure drop is calculated from the air
duct system model based on system resistance
concept - Performance map is used to calculate the air flow
rate
Map Based Gear Pump Model
Condenser
Fan Shroud
Grille
Radiator 1,2
20Test conditions
- Test condition for sizing components and
evaluating cooling system configuration - The thermal management system should be capable
of removing the waste heat generated by the
hardware under extreme operating condition - Grade load condition is found to be most severe
condition for cooling system
Off-Road
Maximum Speed
Grade Load
Ambient Temperature 40 oC
Road profile of off-road condition
21Configuration testGrade Load (30 MPH, 7 )
Engine Speed
Engine BMEP
Battery SOC
Grade Load
Max. SOC 0.7 Min. SOC 0.6 Initial SOC 0.6
22Configuration A and B
- Config. A could not meet the cooling requirements
of electric components
Configuration B
Configuration A
Generator
Generator
Motor
Motor
PowerBus
PowerBus
23Configuration A and B
Configuration B
Configuration A
- Performance of one CAC in Config. B was better
than that of two CAC in Config. A
CAC1
CAC
CAC2
24Configuration B and C
Configuration C
Configuration B
- Config. C is designed by adding a coolant by-pass
line to Oil Cooler in Config. B - Power consumption of pump is reduced by 5 adding
the bypass circuit
25Summary
- The HEV Cooling System Simulation is developed
for the studies of the cooling system design and
configuration - The HEV cooling systems are configured using the
simulation - In hybrid vehicle, the heat rejection from
electric components is considerable compared with
the heat from the engine ( Grade Load heat from
electric components 98kW, heat from engine
module 240kW) - Proper configuration of cooling system is
important for hybrid vehicle components, because
the electric components work independently and
have different target operating temperatures - Parasitic power consumption by the cooling
components can be reduced by optimal
configuration design - Optimization study of cooling system is conducted
using developed model (Symposium II, Optimal
design of electric-hybrid powertrain cooling
system)
26Acknowledgement
- General Dynamics, Land Systems (GDLS)
27Thank you!